Glass compositions and fibers therefrom

ABSTRACT

Fiberizable glass composition with increased levels of BaO are suitable for insulation. These glasses have physical properties which allow current processes to fabricate them into insulation. The glasses also meet proposed German regulations regarding KI≧40.

TECHNICAL FIELD

This invention relates to sodium barium borosilicate glass compositions.Fibers from these compositions make glass fiber insulation.

BACKGROUND OF THE INVENTION

Glass fiber insulation is well known and has been a commercial productfor a long period of time. The insulation is made from intertwined sodalime alumina borosilicate glass fiber which a binder holds together. Thebinder may be any suitable material but quite commonly is aphenolformaldehyde resin or a ureaformaldehyde resin. These binders arewell known and a spray nozzle generally applies them to the glass fibersas hot gases attenuate the fibers from a rotating device, commonlycalled a spinner. A conveyer collects the binder-coated fibers in theform of a blanket, and heat cures the blanket to produce the finalinsulation. The process produces various densities by varying theconveyor speed and the thickness of the cured insulation.

The German government has proposed regulations for glass fibers. Glassfiber compositions meeting the regulations are considered to be free ofsuspicion. The problem, however, for the manufacturer is to produceglass fibers which meet the regulations and standard criteria. Theseglasses must meet the proposed regulations, be fiberizable in standardwool processes, have sufficient durability and have acceptableinsulating properties.

DISCLOSURE OF THE INVENTION

We have developed glass compositions which meet all the criteria. Ourglasses have a high BaO content, a high soda content and contain smallamounts of alumina. The glass compositions meet the proposed Germanregulations. They have a numerical index (KI) greater than or equal to40. Standard wool processes easily produce fibers from thesecompositions. The difference (delta T) between the temperature where theglass has a viscosity of 1,000 poise and the liquidus temperaturegenerally is 50° F. and is often 200° F. or greater. Durability as shownby fiber weight loss is good and is often less than 5% fiber weight lossafter 24 hours in water at 205° F.

Best Mode of Carrying Out Invention

We made measurements of viscosity, liquidus and durability for a numberof glasses with KI≧40. The measurements indicated a compositional regionof glasses which are useful for production of glass fiber insulation.This range is as follows for the major components:

    ______________________________________                                        Ingredients   Weight Percent                                                  ______________________________________                                        SiO.sub.2     45-60                                                           Al.sub.2 O.sub.3                                                                            0-3                                                             B.sub.2 O.sub.3                                                                              0-20                                                           Na.sub.2 O + K.sub.2 O                                                                      12-22                                                           MgO + CaO      0-14                                                           BaO            2-35                                                           ______________________________________                                    

and less than about 10% of any or all of ZnO, TiO₂, Fe₂ O₃, ZrO₂, SrO orLi₂ O, the total being 100% by weight, wherein each glass compositionhas a KI value equal to or greater than 40.

More preferably, the glass compositions consist essentially of:

    ______________________________________                                        Ingredients   Weight Percent                                                  ______________________________________                                        SiO.sub.2     45-57                                                           Al.sub.2 O.sub.3                                                                            0.8-3                                                           B.sub.2 O.sub.3                                                                              0-18                                                           Na.sub.2 O + K.sub.2 O                                                                      12-22                                                           MgO + CaO      0-14                                                           ______________________________________                                    

and less than about 5% of any or all of ZnO, TiO₂, Fe₂ O₃, ZrO₂, SrO orLi₂ O, the total being 100% by weight, and wherein each glasscomposition has a KI value equal to or greater than 40.

Even more preferably, the glass compositions have a BaO content of 5 to30 weight percent and less than about 2% of any or all of ZnO, TiO₂, Fe₂O₃, ZrO₂, SrO or Li₂ O. Even more preferably the glass compositions havea a BaO combat of 12 to 25 weight percent, and less than 2% of any orall of ZnO, TiO₂, Fe₂ O₃, ZrO₂, SrO or Li₂ O.

Insulation products of these glass fibers can be produced from aconventional fiber forming process.

The German regulation requires a numerical index (KI) greater than orequal to 40 to be considered free of suspicion. The index is calculatedby KI=Σ(Na₂ O, K₂ O, CaO, MgO, BaO, B₂ O₃)--2Al₂ O₃. This places severerestrictions on alumina levels and anything not included in the index,such as silica. The obvious choice is to lower alumina to very lowlevels. These glasses, however, have poor durabilities and most couldnot be fiberized by a standard wool process. We discovered that high BaOlevels yielded glasses with significantly improved durability andfiberizability by standard processes.

We designed an array of glasses to show the effect of glass compositionin this narrow field on select properties. All glasses are showntogether with measured properties in the following table.

Examples of the compositions are given in the following table. All theglass compositions have KI index of 40 or higher.

Example 1

Glass fibers of the present invention have the following compositions.Most of the compositions have measured forming temperatures (thetemperature where the viscosity of the glass is about 1,000 poise) andliquidus temperatures.

                                      TABLE                                       __________________________________________________________________________    Weight Percent                                                                Ingredients:                                                                            1   2   3   4   5   6   7   8   9   10  11  12                      __________________________________________________________________________    SiO.sub.2 54.5                                                                              55.0                                                                              56.3                                                                              56.4                                                                              56.5                                                                              56.5                                                                              56.3                                                                              56.4                                                                              54.5                                                                              54.4                                                                              55.2                                                                              54.8                    Al.sub.2 O.sub.3                                                                        0.9 1.0 1.0 1.0 1.0 0.9 1.0 1.0 1.0 1.0 1.6 1.7                     B.sub.2 O.sub.3                                                                         1.5 1.5 15.1                                                                              13.3                                                                              9.8 6.2 13.3                                                                              11.6                                                                              15.2                                                                              15.4                                                                              --  --                      Na.sub.2 O                                                                              12.4                                                                              12.5                                                                              14.5                                                                              14.4                                                                              14.1                                                                              13.8                                                                              14.6                                                                              14.5                                                                              14.5                                                                              14.4                                                                              15.5                                                                              16.5                    K.sub.2 O 6.0 6.0 0.8 0.8 0.7 0.7 0.8 0.8 0.8 0.8 --  --                      MgO       1.1 1.1 2.6 2.6 2.5 2.5 3.1 3.0 2.6 2.6 --  1.8                     CaO       3.1 3.1 7.3 7.1 7.0 6.9 8.5 8.4 7.2 7.2 --  4.0                     BaO       17.8                                                                              17.8                                                                              2.0 4.0 8.0 12.1                                                                              2.0 4.0 2.0 2.0 27.7                                                                              21.2                    TiO.sub.2 --  --  0.1 0.1 0.1 0.1 0.1 0.1 2.0 0.1 --  --                      Fe.sub.2 O.sub. 3                                                                       0.2 0.2 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 --  --                      ZrO.sub.2 2.5 1.8 --  --  --  --  --  --  --  2.0 --  --                      T (°F.) for viscosity                                                            1903                                                                              1882                                                                              1737                                                                              1738                                                                              1761                                                                              1789                                                                              1739                                                                              1747                                                                              1714                                                                              1740                                                                              1882                                                                              1867                    of 1,000 Poise                                                                Liquidus  1524                                                                              --  1498                                                                              1481                                                                              1548                                                                              1553                                                                              1578                                                                              1567                                                                              1538                                                                              1551                                                                              --  --                      Temperature (F°)                                                       KI        40.0                                                                              40.0                                                                              40.3                                                                              40.3                                                                              40.3                                                                              40.3                                                                              40.3                                                                              40.3                                                                              40.3                                                                              40.3                                                                              40.0                                                                              40.0                    durability (% wt                                                                        7.0 --  4.7 4.3 3.8 3.6 --  --  --  --  --  --                      loss of fibers after                                                          24 hrs)*                                                                      __________________________________________________________________________     *Exposure to water at 205° F.                                     

We claim:
 1. Fiberizable glass compositions suitable for insulationconsisting essentially of:

    ______________________________________                                        Ingredients   Weight Percent                                                  ______________________________________                                        SiO.sub.2     45-60                                                           Al.sub.2 O.sub.3                                                                            0-3                                                             B.sub.2 O.sub.3                                                                              0-20                                                           Na.sub.2 O + K.sub.2 O                                                                      12-22                                                           MgO + CaO      0-14                                                           BaO            2-35                                                           ______________________________________                                    

and less than about 10% of any or all of ZnO, TiO₂, Fe₂ O₃, ZrO₂, SrO orLi₂ O, the total being 100% by weight, and wherein each glasscomposition has a KI value equal to or greater than
 40. 2. Fiberizableglass compositions suitable for insulation consisting essentially of:

    ______________________________________                                        Ingredients   Weight Percent                                                  ______________________________________                                        SiO.sub.2     45-57                                                           Al.sub.2 O.sub.3                                                                            0.8-3                                                           B.sub.2 O.sub.3                                                                              0-18                                                           Na.sub.2 O + K.sub.2 O                                                                      12-22                                                           MgO + CaO      0-14                                                           BaO            2-30                                                           ______________________________________                                    

and less than about 5% of any or all of ZnO, TiO₂, Fe₂ O₃, ZrO₂, SrO orLi₂ O, the total being 100% by weight, and wherein each glasscomposition has a KI value equal to or greater than
 40. 3. Glasscompositions according to claim 2 having a BaO content of 5 to 30 weightpercent and less than about 2% of any or all of ZnO, TiO₂, Fe₂ O₃, ZrO₂,SrO or Li₂ O.
 4. Glass compositions according to claim 2 having a BaOcontent of 12 to 25 weight % and less than about 2% of any or all ofZnO, TiO₂, Fe₂ O₃, ZrO₂, SrO or Li₂ O.
 5. Glass compositions accordingto claim 1 having the compositions of:

    ______________________________________                                        Ingredients   Weight Percent                                                  ______________________________________                                        SiO.sub.2     54.5                                                            Al.sub.2 O.sub.3                                                                            0.9                                                             B.sub.2 O.sub.3                                                                             1.5                                                             Na.sub.2 O    12.4                                                            K.sub.2 O     6.0                                                             MgO           1.1                                                             CaO           3.1                                                             BaO           17.8                                                            Fe.sub.2 O.sub.3                                                                            0.2                                                             ZrO.sub.2     2.5                                                             ______________________________________                                    


6. Glass fibers having glass compositions according to claim
 1. 7. Glassfibers having glass compositions according to claim
 2. 8. Glass fibershaving glass compositions according to claim
 3. 9. Glass fibers havingglass compositions according to claim
 4. 10. Glass fibers having glasscompositions according to claim
 5. 11. Glass fiber insulation comprisinga collection of glass fibers according to claim
 6. 12. Glass fiberinsulation comprising a collection of glass fibers according to claim 7.13. Glass fiber insulation comprising a collection of glass fibersaccording to claim
 8. 14. Glass fiber insulation comprising a collectionof glass fibers according to claim
 9. 15. Glass fiber insulationcomprising a collection of glass fibers according to claim 10.